Search Results (50)

This study aimed to explore and identify soil-dwelling nematophagous fungi (NF) from the “El Texcal” Ecological Reserve in Morelos, Mexico, and evaluate their potential as biological control agents against Haemonchus contortus infective larvae (HcL3), a major parasitic threat in livestock systems. The fungi were isolated from soil using the sprinkling of soil on water agar plates. The identification of NF was achieved using morphological identification keys, which was corroborated by molecular procedures using the PCR technique in the ITS4 and ITS5 regions. The nematocidal effects occasioned by these NF were examined through their predatory activity (PA) against HcL3 on water agar plates, and additionally, the larval mortality attributed to their liquid filtrates (LFs) was assessed at three different concentrations (25, 50, and 100 mg/mL) on 96-well microtiter plates. Two NF were identified and classified as two species of Dactylellina genus, namely D. haptospora (Dh) and D. phymatopaga (Dp). The PA exhibited by these NF were 94.79% for Dh and 68.88% for Dp; while their LFs showed 27.83% mortality for Dh and 32.86% for Dp at the highest concentration assessed. While the PA was notably high, the moderate larvicidal effect of the LF suggests that their efficacy may primarily rely on direct physical interaction rather than metabolite-mediated toxicity. The high PA demonstrated by these two isolates of NF indicates that they could be effective candidates for biological control agents against HcL3. Full article

Interactions between species give rise to chemical pathways of communication that regulate the interactions of transboundary species. The communication between nematodes and other species primarily occurs through the regulation of chemicals, with key species including plants, insects, bacteria, and nematode-trapping fungi that are closely associated with nematodes. G protein-coupled receptors (GPCRs) play a crucial role in interspecies communication. Certain flp genes, which function as GPCRs, exert varying degrees of influence on how nematodes interact with other species. These receptors facilitate the transmission of corresponding signals, thereby completing the interactions between species. This paper introduces the interactions between nematodes and other species and discusses the role of GPCRs in these organisms, contributing to a deeper understanding of the impact and significance of GPCRs in cross-border regulation between nematodes and other species. Furthermore, it is essential to leverage GPCRs in efforts to control pests. Full article

Among the most concerning threats impacting global forest ecosystems is the pinewood nematode (Bursaphelenchus xylophilus (Steiner and Buhrer, 1934) Nickle, 1970), the causal agent of pine wilt disease. In Europe, effective management of this pest requires comprehensive regulatory and monitoring strategies, including the annual collection of thousands of wood samples from symptomatic trees and their surroundings, inspection of wood packaging materials like pallets, and the trapping of the insect vector, Monochamus spp., through national networks. Insects and wood samples are sent to official laboratories, where the latter are sometimes incubated at 25 °C for 15 days, aiming to maximize the probability of the detection of the nematode. This study expected to elucidate the effect of the wood incubation process on the detection of B. xylophilus by analyzing wood samples from pallets and green wood obtained from pine stands, both harbouring nematodes in adult and juvenile stages. Additionally, the investigation sought to assess how the presence of fungi, which serve as a food source for the nematodes, enables B. xylophilus to persist in treated pallet wood that is colonized by these fungi. The results indicated that the incubation period is unnecessary for detecting B. xylophilus in pallets, except when the wood is heavily colonized by fungi providing suitable nutrition for the nematodes, although such occurrences are expected to be rare. Furthermore, this study found no significant differences in population growth between the two stages of the nematode’s life cycle. This suggests that second-stage juveniles present in wood samples, despite not undergoing sexual differentiation, do not hinder the reproductive capacity of B. xylophilus. The risk of a potential infestation in treated pallet wood is unlikely if the treatment has been performed correctly, and the incubation does not contribute to increasing the probability of detecting the PWN. Conversely, for samples obtained from trees, the incubation period significantly enhances nematode detection. Full article

The aim of the present research is the isolation and morphological and molecular–phenological identification of nematophagous fungi of Southern Kazakhstan for the production of effective bionematicides on their basis. Nematophagous fungi, which include nematode-trapping, ovicidal, endoparasitic, toxin-producing, and special substance-producing fungi, are among the most effective biological agents in controlling phytoparasitic nematodes. To isolate and characterize nematophagous fungi, soil samples were collected at 12 sites in three regions of Southern Kazakhstan. The samples were collected using the envelope method. The content of nematophagous fungi in the samples was determined using the standard surface sowing technique. The obtained strains of nematophagous fungi were identified. The attractive and nematophagous activity of the obtained fungal strains was determined by using standard methods. In experiments on the isolation and morphological identification of nematophagous fungi, the nematode species Meloidogyne incognita was used. Identification of the strains was carried out by the method of determining the direct nucleotide sequence of the region of the nuclear ribosomal internal transcribed spacer, followed by determination of nucleotide identity with sequences deposited in the international GeneBank database. As a result, the following species of nematophagous fungi living in the soils of agricultural lands in Southern Kazakhstan were identified: Orbilia oligospora, Duddingtonia flagrans, Orbilia oligospora, and Arthrobotrys superba. Full article

During the isolation, identification, and assessment of nematode-trapping fungi (NTF) against nematodes, we discovered an unusual fungus in decaying wood from Morelos State, Mexico. This isolate exhibited some characteristics similar to those of the Arthrobotrys genus; however, we found that it did not match any previously reported species within this genus after conducting morphological and phylogenetic analyses using the ITS, TEF, and RPB2 regions. This new species displays conidiophores with two or three stems emerging from the same initial site and conidiophores with only a single stem and aerial thickened hyphae from which single conidiophores emerge, forming 3D adhesive nets. The conidia, which have one or two septa, range from obovoid to ellipsoidal, crowned by four to six conidia. This report provides evidence that this species has not been described before, and we hereby introduce it as a new species, naming it Arthrobotrys mendozadegivensis. This species displayed a predatory activity of 76.92%, and its liquid culture filtrates in Sweet Potato Dextrose Broth and Czapek–Dox Broth were effective in killing 40.90% and 34.91% of Haemonchus contortus larvae, respectively. This study provides information about a previously unreported species of nematophagous fungus, which is important for systematics and has potential biotechnological applications against nematodes that affect the livestock industry. Full article

The western corn rootworm (WCR) (Diabrotica virgifera virgifera LeConte; Chrysomelidae) is one of the most significant maize pests in Europe, with farmers spending a substantial amount (approximately 140 EUR) on its control. In the context of climate change, WCRs could pose an even greater threat to EU maize production, particularly as the European Union continues to withdraw an increasing number of effective yet environmentally harmful active agents. Biological control methods have now emerged to the forefront in creating sustainable agriculture. In this review, we carried out an extensive literature analysis on methods for forecasting WCRs and evaluated the practical applicability of the latest non-chemical control methods targeting its larvae. Effective forecasting is essential for successful pest management, enabling informed planning and the selection of the most suitable control methods. Several traditional predicting techniques remain in use today, but recent advancements have introduced modern electronic forecasting units combined with sensor-equipped pheromone and colour traps, as well as thermal sum calculations. Research has demonstrated that crop rotation is one of the most effective methods for controlling WCR larvae. Biological agents, such as entomopathogenic fungi (Beauveria bossiana and Mettarrhyzum anasoplia), entomopathogenic nematodes (Heterorhabditis bacteriophora), and botanical insecticides such as azadirachtin can significantly reduce larval populations and root damage, thereby maintaining infestation levels below the economic threshold. Genetically modified maize plants that produce specific toxins, along with conventional breeding efforts to increase root system regeneration, are also promising tools for the sustainable management of this pest. This review summarizes the solutions for prediction of western corn rootworm infestations and non-chemical control of its larvae. Accurate forecasting methods provide a clear picture of infestation levels in a given area, enabling precisely targeted control measures. In all cases, the control should be directed primarily against the larvae, thereby reducing root damage and reducing the size of the emerging imago population. This review demonstrates that biological control methods targeting larvae can be as effective as pesticides, supporting sustainable pest management. Full article

The carnivorous fungus Drechslerella dactyloides can form constricting rings through hyphal specialization to capture nematodes. The formation of constricting rings is a prerequisite for capturing nematodes and a characteristic of entering the carnivorous stage. Currently, there is limited research on the molecular mechanism of constricting ring formation. In this study, two D. dactyloides mutants unable to form constricting rings were obtained through UV irradiation mutagenesis, and their growth and development phenotypes were compared with the wild-type strain. Transcriptome comparisons revealed differences between the mutants and the wild-type strain in metabolic pathways related to cell wall structure, peroxisomes, lipid metabolism, and MAPK signal transduction, which we validated through qPCR. We further deleted one differentially expressed gene, DdSTE2, of the MAPK pathway and confirmed its role in conidiogenesis and trap formation in D. dactyloides. Together, our results indicate that the remodeling of cell wall structure, peroxisomes, lipid metabolism, and MAPK signal transduction pathways are involved in the formation and maturation of D. dactyloides constricting rings. We discuss the implications of these results for utilizing these fungi to control animal and plant parasitic nematodes. Full article

Electron transfer flavoprotein (ETF) plays an important function in fatty acid beta oxidation and the amino acid metabolic pathway. It can provide pathogenicity to some opportunistic fungi via modulating cellular metabolite composition. Arthrobotrys oligospora is a typical invasion fungus to nematodes. Its ETF characterization is still unknown. Here, we showed that the mutations of A. oligospora ETF (Aoetfα and Aoetfβ) and its dehydrogenase (Aoetfdh) led to severe defects in mitochondrial integrity and blocked fatty acid metabolism. The pathogenicity-associated trap structures were completely suppressed when exposed to nematode-derived ascarosides and nutrition signals, including ammonia and urea. Compared to the wild-type strain, the nematode predatory activity was significantly reduced and delayed. But surprisingly, the rich nutrition could restore the massive trap and robust predatory activity in the mutant Aoetfβ beyond all induction cues. Moreover, the deletion of Aoetfβ has led to the accumulation of butyrate-like smell, which has a strong attraction to Caenorhabditis elegans nematodes. Ultimately, ETF and its dehydrogenase play a crucial role in nematode-trapping fungi, highlighting mitochondrial metabolite fluctuations that are connected to pathogenesis and further regulating the interactions between fungi and nematodes. Full article

Arthrobotrys oligospora is a representative nematode-trapping (NT) fungus that is able to capture, kill, and digest nematodes by producing specialized three-dimensional networks (traps) under nutrient-deprived conditions. Ran1 is a serine/threonine protein kinase that can act as a negative regulator of sexual conjugation and meiosis. However, the specific role of Ran1 remains largely unknown in NT fungi. Here, we identified AoRan1 (AOL_s00004g277) via gene disruption, phenotypic analysis, and metabolomic analysis. Our findings reveal that Aoran1 knockout caused a remarkable increase in conidial production, traps, and nematode feeding efficiency. In addition, the absence of Aoran1 resulted in the accumulation of lipid droplets and increased autophagic levels as well as increased tolerance to cell wall synthesis-disturbing reagents and oxidants. Metabolomic analyses also suggested that AoRan1 is involved in multiple metabolic processes, such as fatty acid biosynthesis. In summary, our results suggest that AoRan1 is crucial in conidiation, pathogenicity, and secondary metabolism. This study’s results further our understanding of the molecular mechanisms by which AoRan1 regulates conidiation and trap formation in A. oligospora. Full article

Plant pathogenic nematodes play an important role in crop production and are difficult to control. One of them is Heterodera schachtii—a cyst nematode, pathogenic to sugar beet. Nature suggests a natural way to resolve this problem by using nematode-trapping fungi, one of which is Pleurotus ostreatus. It is one of the most widespread mushrooms in the world. It is a valuable and widely cultivated edible mushroom with nematocidal properties. The mycelium of this mushroom produces toxin droplets that paralyze nematodes, after which the nematodes become infected with the hyphae filament, resulting in their death. This feature can be put to practical use as a natural nematocidal agent. In this paper, we have described studies on the variability of the nematocidal properties in the progeny of three wild strains of P. ostreatus (Po1, Po2, Po4), obtained by crossing dikaryons with monokaryons (Buller phenomenon). The toxicity of mycelium was tested against the model organism Caenorhabditis elegans and against sugar beet pest—H. schachtii. The results of the study allowed the selection of the progeny heterokaryotic mycelia with the best parameters useful for in vitro control of both nematodes. They differed in the activity against C. elegans and H. schachtii, and in the toxic knobs production. The results indicated that the progeny of the Po1 strain presented a good ability to produce hyphal knobs in the presence of C. elegans, and progenies of the Po4 strain presented good quality of growth in preferred temperatures (10–25 °C). Three strains Po1 5dix27, Po2 20dix21, and Po4 2dix1, as well as a maternal strain Po4 controlled H. schachtii by entwining cysts better than other strains. These strains were moderately effective against C. elegans. Strains Po2 15dix17, Po4 1dix18, and Po4 1dix30 may be considered good controlling isolates against both tested organisms. The results of the research also clearly suggest that the killing properties of P. ostreatus mycelia should not be assessed only by their ability to produce toxic hyphal knobs. Their nematocidal properties also depend on other mechanisms developed by mycelia, which is observed as the lethality of nematodes. The results of this research will lead to a natural way to protect plants against nematodes. The research also proved the nematocidal properties of the wild strains to reduce the H. schachtii population in the soil. Full article

Light is a key environmental factor affecting conidiation in filamentous fungi. The cryptochrome/photolyase CryA, a blue-light receptor, is involved in fungal development. In the present study, a homologous CryA (AoCryA) was identified from the widely occurring nematode-trapping (NT) fungus Arthrobotrys oligospora, and its roles in the mycelial growth and development of A. oligospora were characterized using gene knockout, phenotypic comparison, staining technique, and metabolome analysis. The inactivation of AocryA caused a substantial decrease in spore yields in dark conditions but did not affect spore yields in the wild-type (WT) and ∆AocryA mutant strains in light conditions. Corresponding to the decrease in spore production, the transcription of sporulation-related genes was also significantly downregulated in dark conditions. Contrarily, the ∆AocryA mutants showed a substantial increase in trap formation in dark conditions, while the trap production and nematode-trapping abilities of the WT and mutant strains significantly decreased in light conditions. In addition, lipid droplet accumulation increased in the ∆AocryA mutant in dark conditions, and the mutants showed an increased tolerance to sorbitol, while light contributed to the synthesis of carotenoids. Finally, AoCryA was found to affect secondary metabolic processes. These results reveal, for the first time, the function of a homologous cryptochrome in NT fungi. Full article

Nematode-trapping (NT) fungi are a major resource for controlling parasitic nematodes. Arthrobotrys flagrans, as a typical NT fungus, can capture nematodes by producing three-dimensional nets. The APSES transcription factor Swi6 plays a vital role in fungal growth and the pathogenicity of pathogens. In this study, we characterized AfSwi6 via gene disruption using the homologous recombinant method and transcriptome sequencing. Knockout of the AfSwi6 gene caused defects in mycelial growth, trap formation and pathogenicity, chlamydospore production, and stress response. Moreover, the transcriptome data indicated that AfSwi6 was related to DNA repair, stress response, and plasma membrane fusion. The result showed that AfSwi6 has a significant effect on trap development and chlamydospore production in A. flagrans. Full article

Arthrobotrys oligospora is a typical nematode-trapping (NT) fungus, which can secrete food cues to lure, capture, and digest nematodes by triggering the production of adhesive networks (traps). Based on genomic and proteomic analyses, multiple pathogenic genes and proteins involved in trap formation have been characterized; however, there are numerous uncharacterized genes that play important roles in trap formation. The functional studies of these unknown genes are helpful in systematically elucidating the complex interactions between A. oligospora and nematode hosts. In this study, we screened the gene AOL_s00004g24 (Ao4g24). This gene is similar to the SWI/SNF chromatin remodeling complex, which was found to play a potential role in trap formation in our previous transcriptome analysis. Here, we characterized the function of Ao4g24 by gene disruption, phenotypic analysis, and metabolomics. The deletion of Ao4g24 led to a remarkable decrease in conidia yield, trap formation, and secondary metabolites. Meanwhile, the absence of Ao4g24 influenced the mitochondrial membrane potential, ATP content, autophagy, ROS level, and stress response. These results indicate that Ao4g24 has crucial functions in sporulation, trap formation, and pathogenicity in NT fungi. Our study provides a reference for understanding the role of unidentified genes in mycelium growth and trap formation in NT fungi. Full article

The capsule-associated protein 10 gene (CAP10) is indispensable due to its involvement in pod formation and virulence maintenance in Cryptococcus neoformans. The function of the CAP10 gene in nematode-predatory fungi remains unreported. As a typical nematode-trapping fungus, Dactylellina haptotyla efficiently captures nematodes using adhesive knobs, which has potential applications in the biological control of plant-parasitic nematodes. In this study, we investigated the function of DHXT1 (a CAP10 homologous protein) in D. haptotyla–nematode interactions based on the disruption and overexpression of DHXT1, phenotypic analysis and metabolomic analysis. As a result, it was shown that the disruption of the DHXT1 gene causes a marked decrease in the number of adhesive knobs, and on the contrary, the overexpression of the DHXT1 gene causes a substantial increase in the number of adhesive knobs. Interestingly, the variety of metabolites increased with the disruption of the DHXT1 and decreased with the overexpression of the DHXT1 gene. The results suggest that DHXT1 effects pathogenicity through its involvement in adhesive knobs’ formation and metabolite synthesis and serves as a key virulence factor in D. haptotyla. Full article

Arthrobotrys oligospora, a widespread nematode-trapping fungus which can produce conidia for asexual reproduction and form trapping devices (traps) to catch nematodes. However, little is known about the sporulation mechanism of A. oligospora. This research characterized the functions and regulatory roles of the upstream spore-producing regulatory genes, AosfgA and AofluG, in A. oligospora. Our analysis showed that AosfgA and AofluG interacted with each other. Meanwhile, the AofluG gene was downregulated in the ΔAosfgA mutant strain, indicating that AosfgA positively regulates AofluG. Loss of the AosfgA and AofluG genes led to shorter hyphae and more septa, and the ΔAosfgA strain responded to heat and chemical stresses. Surprisingly, the number of nuclei was increased in the mycelia but reduced in the conidia of the ΔAosfgA and ΔAofluG mutants. In addition, after nematode induction, the number and volume of vacuoles were remarkably increased in the ΔAosfgA and ΔAofluG mutant strains. The abundance of metabolites was markedly decreased in the ΔAosfgA and ΔAofluG mutant strains. Collectively, the AosfgA and AofluG genes play critical roles in mycelial development, and they are also involved in vacuole assembly, the stress response, and secondary metabolism. Our study provides distinct insights into the regulatory mechanism of sporulation in nematode-trapping fungi. Full article